1. Field of the Invention
This invention relates to a wave energy absorber or a wave-power converter mountable on a wall structure to break waves, and more particularly to a resonant type wave energy absorber mountable as a part of a breakwater, a coastal embankment, or similar wall structure at a minimum installation cost and with a maximum energy absorbing efficiency for extracting low-cost energy from waves such as ocean waves. The output from the wave energy absorber of the invention can be used in the form of electric power by energy conversion through an electric power generating means attached to the wave energy absorber or can be stored in the form of oil pressure by energy conversion through a hydraulic means attached to the wave energy absorber.
2. Description of the Prior Art
Wave energy absorbers which have been proposed heretofore can be generally classified into the categories of Table 1.
TABLE 1 ______________________________________ Place of installation and construction Dynamics ______________________________________ I. Coastal fixed construction 1. Passive type II. Offshore float construction 2. Resonant type ______________________________________
From the standpoint at efficiency of energy extraction, it is well known that the second type of dynamics, i.e., the resonant type, of the aforementioned classification of Table 1 is better than the passive type. However, most of the conventional wave energy absorbers of the resonant type are built in the form of the offshore float construction, i.e., the category II of Table 1, which construction is inherently costly because a large floating body is required and because the difficult problem of mooring the floating body remains unsolved. On the other hand, a coastal fixed construction can be built as a part of a breakwater, a coastal embankment or the like with a considerable saving in the installation cost, but only the dynamically passive type has been proposed for the coastal fixed construction and the resonant type coastal fixed construction has never been proposed.